"The management completely rejects the allegations (and notes that Muddy Waters Research has publicly stated that it has taken a short position in Noble Group's shares),'' Noble said, adding that it is studying the report in detail.

Earlier on Thursday, Muddy Waters - the short-sellers which had in 2012 questioned the accounting practice of Singapore-listed commodities group Olam International - said it "is short Noble Group Limited'', and said Noble has been free cash flow positive only four out of 20 years.

"We are really short Noble's management. With a company as complex and opaque as Noble, there is no way for investors to definitively answer certain key questions. It becomes a question of how much investors should trust Noble's management to be straight with them. Noble's management has adamantly insisted that its accounting is conservative, and by implication, is reflective of reality. We do not believe Noble's management,'' Muddy Waters said.